Hi.
Since you requested assistance with the English in this product, I'd like to assist.
"Note: this does have sense only for different Pub/Sub topics."
suggest:
"NB: this makes sense only when the pub and sub topics differ."
(It's one of those English expressions which has no sense!)
"If you need not a switch, but a simple button,"
suggest:
"If you need a simple button rather than a switch,"
There are more. I will pick them out over time.
Hoe this is useful.